This is the start a series of posts about the notes I made when I read the source code of popular open source projects. I myself learned a lot from digging into the code of open source projects. I hope it can help you too. I will start with Loki, a log aggregation system inspired by Prometheus. Overview grafana/loki consists two components: Loki: the log aggregation system Promtail: the agent to collect logs and send to Loki in a nutshell, loki and promtail is a service-client arhitecture.